Air-heater.



P. RUSSELL, F. J. SEPAS L E. B. WILFORD.

vAI'R HEATER. i APPLICATiON FILED JAN. 30.1914. RENEWED NOV. 17,1915. y

Patented May 22, 1917.

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AND EDWARD iB.' WILFORD, OF MERION BOROUGH, PENNSYLVANIA, vASSIGrNORS TO ELECTRO DENTAL MANUFACTURING VANIA, A- CORPORATIONOF PENNSYiV ANIA.'

AIR-HEATER.

Application led January 30, 1914, Serial No. 815,507.

signedv to heat a flowing body of air as re! quired in dental syringes and like instruments, it being especiall7 desired that the construction shall be such as to prevent objectionable heating of the of the device and consequent lowering of the efficiency of the apparatus.

l/Ve also desire to provide a device for electricallyheating air, which in addition to being substantial and relatively inexpensive to construct, shall be'conveiiient 'to use and safe to operate.

Another object of the invention is to provide a novel forni of air heating device in which the heat generating element -niay be conveniently removed4 or'replaced for the purpose of inspection, repair, etc., and in which the air is caused to take a tortuous course with a view to preventing the external portions of the apparatus from becoming highly heated.

rEhese objects and other advantageous ends we secure as hereinafter set forth, reference being had to the accompanying drawings, in which Figure 1 is a longitudinal vertical section of a part of a hot air syringe constructed according to our invention;

Figs. 2, 8 and 4 are respectively transon the lines ze-a, 72- and 0-c, of Fig. l;

Fig. 5 is va vertical section of a detail of the invention, and

F ig. 6 is a perspective view of one end of the heating' unit. l

1n the above drawings, 1 represents a metallic tube internally threaded at one end and externally threaded at the opposite end. 0n this latter end is threaded an inwardly Specification of Letters Patent.

exterior pi i'tions Patented May 22, 1917. Renewed Novemberl?, 1915. Serial No. 62,075.

flanged sleeve 2, while the other end has threaded into it a sheath 3 of some material which is a non-conductor of heat and elec# tricity.' v

A metallic member 4.

nector, extends into the constituting a conflanged end of the n sleeve Q, to which it is rigidly connected by having at one end an inwardly extending flange 6 land coperating with an annular shoulder 7 on the coniiector l, from which, however, it is electrically insulated b v al ring 8, of liber, mica, or the like. rllliis second sleeve 5 likewise has an annular shoulder 9, between which g and the flange of the sleeve 2 is confined a second insulating ring 10.

W ith the ,above described, construction, the second sleeve 5 is spaced away from the connectorpal and has a series of holes 12, whereby air may pass from the annular space around the connector to the annular space between the sleeves 5 and 2;-such air being free to pass from this latter space between the second sleeve and the tube 1 to the interior latter. The connector 4; at one end is internally threaded for the reception of the air supply pipe 13, and it also has a series of radially extending holes 4a, through which air is free to pass from tliissupply pipe to j the annular space within the second sleeve 5. The part of the air supply pipe 13 immediately adjacent its threaded end above referred to is tapered and has rotatably mounted on it a valve 14 in the form of a sleeve internally bored to fit said tapered portion and iii addition having an elongated internal slot or recess 15 extending parallel with its axial line in position for connecting two radially extending passages 16 and 17 leading respectively to the interior ofthe connector l and to the source of air. By rotating the valve 14 it is thus possible to cut olf or establish communication at will between these passages 16 and 17, and we preferably provide a spring washer 18 between tlie valve and the adjacent end of the connector 11, whereby said valve is at all times kept in air-tiglit contact with the tapered end of the supply pipe 13.

Mounted on and fixed to the valve 14 is a. v

of the main portion ofv the4 erably having a corrugated or ribbed exand is preferably ternal surface and recessed at one end to receive the projecting ends of the connector 4 and of the sleeve 5. In order to limit the possible angle through which the handle '19 with the valve 14 may be turned relatively key to the supply pipe 13, We provide a 20 driven into or otherwise attached to said handle and projecting into a recess 2l formed in a flange 22 of the pipe.

Extending longitudinally through the,

handle 19 is yan electric conductor 23, to which is electrically connected a spring contact member 24 yieldingly engaging the outer cylindrical surface of the sleeve 5, and one terminal of an electric circuit may be connected to this member 23, while the other terminal of such circuit` is connected to the supply pipe 13.

The outer casing 1 just inside its internal threads has an inwardly projecting shoulder 26 against which a ring27 of suitable insulating material is held by means of a notched ring 23 Fig. 5 abutting against the adjacent end of a tube forming an inner casing 29, whose opposite end is electrically insulated by a non-conducting ring 31 from a. shoulder 30 at the inner end of the connector 4. This casing 29 is substantially concentric with the outer casing 1 from whose inner surface it is spaced away, and the notches of the ring 28 form passages 37 between said ring and the adjacent end of said casing 29, through .which air is free to pass into the space between the inner casing surface and a metallic tube 32. This latter extends concentrically within the inner casing 29, being inwardly flanged at "one end Yand provided with an insulating lining 33. j

Mounted Within said tube and forming with it a removable heating unit is an elongated coil or other body of wire or current conductor', preferably having a high specific resistance as well as a high melting point, and while one end of this coil is sweated into or otherwise electrically` connected to a screw 34, its other end is enf gaged and supported by a suitably formed bar 35 extending across the opposite end of the tube 32 as shown in Fig. 6. Said bar is preferably cross shaped with two of its extremities removably held in an annular recess in the end of the tube 32 which at two opposite points 50 is notched so as to hold the two other ends of saidbar for the purpose of preventing its rotation. The coil 43 is maintained in a state of tension formed onl a mandrel of other than circular section,

small angle relatively to those on either side 'of it, as shown in Fig. 2, in order that so or covereach other.

-The air through the heating unit and is effectively' vtube 32 1s at a after which eachA `of its convolutions is rotated through a This heating unit is rigidly held to the connector 4 by the screw 34 threaded centrally into the same and rigidly connected -to the inwardly flanged end of the tube 32 by a pair of nuts, which, however, are electrically insulated from it.

Air passages 36 are provided through the side walls of the tube 32 and its lining, immediately 4adjacent the screw 34 and there is an annular space between it and the inner surface of the casing 29, which is connected by openings 37 with the space between said inner casing andthe outer casing 1.

The nozzle 33 of the syringe has sweated or otherwise fixed to its base a ball 39 which.

is rotatable within a socket 40 formed by a sleeve threaded into the sheath 3. The outer edge of this socket sleeve is bent inwardly as shown, in order to retain the ball in place and there isa spring 41 confined between a retaining flange 42 of said socket and the ball, so that the latter is at all times kept in air-tight engagementwith the inwardly curved portion of said socket 40.

Under conditions of use the electric currentiows from a suitable supply conductor to the member 23, thence through the spring 24 to the ring 5, through the inner casing 29, notched piece 28, end 'of tube 32, and cross-bar 35 to one end of the heating coil 43. From the other end of this latter the current flows to the screw now air Abe delivered to the supply pipe 13 and the handle 19 be rotated so that the recess 15 of the valve is in the position shown in Fig. 1, connecting the parts 16 and 17 of the passage in said conduit, such air will flow into the connector 4, out through the openings 4a thereof, thence through the openings 12 of the sleeve 5, into the space between the inner casing 29 and the outer casing 1 and so to the forward end of the device adjacent the nozzle. From here it .passes into the space betweentthe inner casing 29 and the tube 32, thence to the rear or inner end of said tube and through the openings 36 into the interior thereof. thus admitted vpasses forward heated by its intimate contact with the heated convolutions of the wire 43, being finally allowed to pass in a heated condiltion into the nozzle 33, from the end of which it escapes. As will be understood by -those skilled in the art, the flow of the cool 34, thence to thel connector 4 and to the supply pipe If.

air over the inner surface of the outer casing 1 keeps this at a low temperature regardless,v of the fact that the air within the high temperature, and any heat radiated from said tube is carried by the air back into the heating chamber and finally out through' the nozzle.

' ABy the use of the heat insulating sheathl 3, any material conduction of heat from the nozzle to the outer casing is effectually pre.

" ing coil suspended in said tube;

tube. This 'is provided with oppositely dis- 1 posed recesses 50, which, in addition to holding the ends ofthe bar 35; are designed for the reception of a screw-driver and by this means it is possible to rotate said tube so as to withdraw the screw 34 from the connector 4; whereupon said tube may be removed from the remainder ofthe device.

By the mounting and construction of the nozzle and its associated parts, it is possible to move it into any of a numbeilof positions at different angles to .the general line of the casing l.

We claim l. The combination in an air heater of a casing having an inlet; an outlet conduit; a heating unit in the casing connected to receive air from the inlet and deliver it to the outlet conduit; with a non-conducting sheathvremovably connecting the casing and the outlet conduit, and extending over that part of said conduit adjacent the casing.

2. The combination in an air heater of a casing having an inlet; an outlet conduit; a heating unit in the casing connected to receive air from the inlet and deliver it to the outlet conduit; a socket carried by the casing; a ball member attached to the outlet conduit and ope' itive in the socket; and a spring in said socket operative upon the ball structure to cause the latter to make a tight joint with said socket.

3. The combination in an air heater of a casing having an inlet; an outlet conduit; a heating unit in the casing connected to receive air from the inlet and deliver it to the outlet conduit; with a ball and socket joint connecting the casing and the outlet conduit and including a heat insulating sheath.

4. The combination in an air heater of a casing having an inlet and an outlet; a heating unit consisting of a tubel detachably screwed into said casing and communicating with said inlet and outlet; and a heat- 5. The combination in an air heater of a casing; ahandle having two electric conductors, of'wliich oneis an air conduit; a` tube in the casing; an electric conductor in thetube having one end" electrically connected thereto and its other end electrically connected to said air conduit; and an inner casing electrically connected to said tube and to the second electric conductor.

a tubular casing 6. The combination in an air heater of a casing; a handle having two electric conductors; of which one is an air conduit; a tube in the casing; an electric conductor in the tube .having one end electrically connected thereto and its other end electrically connected to said air conduit; an inner casing electrically connected to said tube and to the second electric conductor; there being passages for conducting air from the con-` duit in the handle to the tube; with an outlet conduit connected to receive the air from said tube. y

7. The combination inan air heater, of a casing having an inlet; an outlet nozzle for' said casing; a connector in the casing; two tubes, of which one abuts on but is insulated from the connector', and the other is threaded to said connector; with a heating coil in the second tube and removable therewith from the casing.

S. The vcombination in an air heater, of a conduit; a connector mounted thereon and having air passages; a casing mounted to receive air from said passages; a sleeve in said casing receiving' air therefrom; an outlet'nozzle; and a tubular heating unit removably mounted in the sleeve in position to heat air therefrom and deliver it to 'the nozzle.

9. The combination in an air heater of at leait three nested substantially concentric tubes of progressively increasing diameters; means for maintaining the intermediate one of said tubes in a state of compression and the inner and outer tubes in a state of tension; with a heating coil in the innermost tube.

l0. The combination in an air heater of a tubular casing; a heatingunit therein consisting of a tube provided with a threaded end portion electrically insulated from its body and `a'heatiiig coil having its ends respectively connected to said body and to said end portion; an outlet nozzle for. the casing; a metallic connector-having the end portion of the heating unit removably screwed into it; with means for conducting electric current to the body of the tube and to said metallic connector.

ll. The combination in an air heater; of a tubular casing; a heating coil in said casing; an outlet nozzle at one end of the casing; a connector at the opposite end of the casing having an air inlet passage and electrically connected to one terminalA of the heating coil; with a tubular structure surrounding .said coil Within the casing and connected. to the other terminal of tliecoil. 12. The -combination'in an air heater; of

ing; an outlet nozzle vat one end of the casing; a connector at the opposite e-nd`of the casing having an air inlet passage and electrically connected to one terminal of the a, heating coil in said 'casa heating coil; with a tubular structure surrounding said coil within the casingfin position to serve as a baffle for the air flowingv from the passage of the connector through the casing to the nozzle.

13. The combination in an air heater of a tubular casing; two sleeves mounted concentrically within the same and including means eoactiiig therewith to form a tortuous air passage; a heating coil carried by and freely suspended within the inner sleeve and removable therewith as a. unit from tlie other' sleeve and from the. casing; a source of current connected to one of the sleeves and to one end of said coil; and means for electrically connecting said sleeve to the second end of the coil.

1l. The combination in an air heater, of a tubular casing; a heating coil in said casing; an outlet nozzle at one end of the casing; a connector at the opposite end of the casing having an air inlet passage land electrically connected to one terminal of the heating coil; with a plurality of tubular structures surrounding said coil within the casing in position to serve as baiiies for the air flowing from the passage of the connector through the casing to the nozzle.

.15. The combination in a fluid heater of a plurality of sleevesfitting one inside the other to form a tortuous passage; an inlet conduit connected to deliver air to the outer portions of said passage; a heating member freely suspended within the cylindricalihollow of the innermost sleeve and arranged to `receive and heat air after it has ilowed through said passage, one of the sleeves being connected to conduct current to one terminal ot said heating member; means for conducting current to said latter sleeve and the second terminal of the heating member; and an oilltlet 'conduit for the heated air.

16. The combination in an air heater of a casing having an inlet and an outlet; a heating'elenien-t in the casing connected to receive air from the inlet and deliver it to the outlet; with means for preventing conduction of heat from the heating element to the casing7 the same consisting of a member placed to direct `the incoming cool air into contact with the inner surface of the casing before permitting -it to pass to the heatingy element.

17. The combination 1n an air 'heater of an outer casing havirg an inlet and an outlet; a heating unit in said casing connected to receive air from the inlet and deliver it to the outlet; and an inner casing mounted to conduct incoming cool air between the outer casing and the .heating unit to prevent heating of said outer casing.

18. The combination in an air heater of an outer easing having an inlet and an outlet; a heating unit connected to receive air from the inlet and deliver it to the outlet; with an elongated inner casing interposed between the heating unit and the outer casing. provided with passages placed to iii-st direct cool air from the inlet between the inner and outer casings and thereafter conduct such air between said 'inner casing and the heating unit before permitting it to pass into tlie lattei.

19. The combination in an air heater' of an outer casing; a tube closed at one end and mounted in said casing; a heating coil in said tube; an inner casingl for conducting air to the interior of the tube adjacent the closed end thereof; and an outlet conduit connected to the easing vin position to directly receive heated air discharged from the tube.

names to this specification in the presence of two subscribing witnesses.

PER-CY RUSSELL. FRANK J. SEPAS. EDWARD B. WILFORD.

Vitnesses:

ViLLLxyI E. BRADLEY, WM. A. BARR.

In testimony whereof we have signed our 

